Draft-controlling means for tank heaters



July w, 1923.

G. W. MUNDIE DRAFT CONTROLLING MEANS FOR TANK HEATERS Filed April 7, 1923 STATE-s P EN Fri-cs;

GEORGE w. MUNDIE, or PERU, ILLINOIS.

naar'r-oonrrnonmne roa TANK um;

Application filed April 7,1923. Serial 110,630,507."

T0 altwhomit may concern);- V

Be "itknown that'I, Gnonon W. MUNDIE, a citizenof the'United States, residing at Peru, inthe county of La Salle and State of Illinois, have invented certain new anduseful Improvements in Draft-Controlling,

Means'forTankHeatei's, of whichthe following a specification, reference being had to thejaccompanying drawings.

This invention relates, to tank heaters, and

particularly to tank heaters of the character shown in Patent No. 908,182, of -December 29, 1908,-and No. 966,147, of August 2, 1910.

In heaters of this character there has been provided a fire box with a grate and a flue leading from the upper end of the fire box, with adamper disposed just below the flue and resting upon one end of aba-ffle plate extending longitudinally of the heater and adjacent the upper wall thereof, this baffle defining a return flue. WVhen the fire is first started in a heater of this character,

the damper is turned to such a position as will permit the products of Combustion to pass directly upward without going through the return flue and pass directly out through the discharge flue or smoke pipe. In heaters of this character as placed upon the market, this damper rests loosely upon a seat formed at the inner end of the baffle and the damper is operated by a wire extending through the smoke'pipe at the base thereof and connected to an arm on the damper. It has been found that in assembling this heater this damper is very liable to be reversed in position upon I its seat so that the arm instead of extending toward the opening through which the wirepasses extends reversely thereto and this gives rise to troubles in the operation of the device. Thus, for'instance, if the clamp er is turned around from its correct position the diagonal shank of the damperholds the damper open at all times, letting all the heat go directly up the chimney and not diverting the products of combustion through the return flue, as is necessary to secure proper heating results after the fire has beenstarted.

Furthermore, it has-been found the case thatthe user loses the damper during the warmer months of the year when it is not Iieces sary to operate the heater.

The object of the present invention is to do away entirely with this damper and provide means which does not require adjustment and which is permanently disposed in position so that it cannotbelost, which will? act when the fire is first built" to conduct the products of combustion direc tly tothej smoke pipe or outlet discharge flue and when the fire has become fullystarted will act jto to I automatically cause the products of combii sij tion to pass throughthereturn flue and thus impede the passage of the combustion prod ucts and cause them to give out more heatto the water surrounding. the tank. I

The invention is illustratedlin the accompanying drawings, wherein II I t Figure l is a side elevationof one section" A of my heater looking at' the inside face thereof; I v Figure 2 is a section through both sections r of the complete heater on the line 2-2 of Figure l; t I I I Figure 3 is a fragmentary top plan view of the complete heater. I i Referring to these drawings, it will be; seen 'thatI have illustrated a tank heater of the general character shown in the patents before referred to. This heater is'formed II in two mam sections A and 13, these sections being identical and being formedwith confronting marginal flanges whereby the sec: tlons may be joined to form the complete heater. These sections A and B are 180 formed as to provide a fire box 10 within '85 which a grate 11 is normally disposed, there I being a: fuel chute 12 extending down into" the fire box. I

As illustrated in Figure 3, the upper por tion of the heater casing is contracted -in 00" the two sections Aand B, as shown in Figure 2, has extending from its lower edge the downwardly and laterally extending damper wall'16. This wall is, of course, I formed in two sections,'one section being a cast with the section A of the casing and the other section being cast with the section o B. A baflle 17 extends in one direction from" the lower'end of the wall16, this; baflie-ibe-j ing formed inftwo sections. I Immediately; above this battle the return flue as at 18, to form a relativelynarrow passage":

which merges into the relatively large pore tion of the return flue 13. Heaters of this type are all formed with the baiiie 1.7 and the contracted portion 18 immediately above is constricted, 1

it merging into the return flue and hence the formation of the heater in this regard does not require any particular description.

My invention consists in providing the damper wall 16 and forming in this wall the elliptical opening 19. This opening has its major axis extending transversely of the heater and the lower edge of this opening is disposed just above the contractechportion 18. I have found by a series of tests lasting over a number of years that the elliptical form of opening is particularly necessary and that it is particularly necessary that this opening should be located just above the narrowed or contracted portion 18 and that the opening should have a major diameter of approximately 351-, with a minor diameter slightly less than two inches. Of course, I do not wish to be limited to the exact situation of this opening or the proportions of the opening. Nevertheless I find an opening located as described and having the proportions stated to be particularly effective.

As before remarked, I do away entirely with the movable damper which is ordinarily located at the inner end of the baffle 17 and which is shiftable to permit all the products of combustion to pass up through the discharge flue 1 1 or to cause the proclucts of combustion to pass beneath the baflle 17 and around and into the return flue and so out of the discharge flue. I have found by experiments conducted over a considerable time that the position of the hole 19 as shown secures the best results for the reason that the force of the draft around the return flue when the volume of the fire was increased to normal effectually prevented any draft through this opening 19 and best preserved the efficiency of the heating by the return flue. I have found also that if this opening is placed up higher than the position shown in Figure 1 it does not operate so well, presumably because the heat from the return flue is deflected by the solid plate below the opening 19 which deprives it of the necessary force to prevent inflow of products of combustion through the opening 19 in the flue 14. I have also found that forming this opening 19 elliptical in shape gives much better results than where the opening 19 is circular. This is due to the fact apparently that the shape of this opening spread out the draft passing through the opening which resulted in it being much more efl'ectually closed when in normal op eration from the fact, as I reason it, that the draft from the return flue has more area with less resistance to work against than if the opening were circular. It will be understood, of course, that when the fire is started the products of combustion will take the shortest course and pass directly up through the opening 19 and through the flue 14. After the the has been started, however, and combustion products are evolved in relatively large quantities, they will pass both ways, one current passing up through the opening 19 and the other current passing around the baffle 17 and so into the return flue 13, until the force of the draft around the return flue increases to its normal extent, at which time there is so much pressure of the products of combustion on one side of the opening 19 as to prevent the direct discharge of combustion products through this opening 19.

It will be seen that this invention simplifies the construction of heaters of this character, that it eliminates the movable damper plate with its attendant objections, and that it acts automatically to control the passage of the combustion products Without the necessity of adjustment.

I claim 1. In a tank heater, a fire box, a discharge flue disposed immediately above the fire box,

a wall extending downward from one wall of the" discharge flue and having a draft opening therethrough, and a bafiie extending transversely through the axis of the discharge flue and from the lower end of the wall and defining a return flue between it and the top of the heater. I

2. In a tank heater, a fire box, a discharge flue disposed immediately above the fire box, a wall extending downward from one wall of the discharge flue and having a draft opening therethrough, and a bafile extending transversely through the axis of the dis charge flue and from the lower end of the wall and defining a return flue between it and the top of the heater, the return flue immediately above the baffle being constricted for approximately the length of the baffle, the opening being disposed on a level slightly above the said constricted portion.

3. In a tank heater, a fire box a discharge flue disposed directly above the fire box, a wall extending downward at an inclination from one wall of the flue and having a draft opening therethrough, and a baflie extending transversely of the axis of the flue and from the lower end of the wall and defining a return flue between it and the top of the heater, said return flue immediately above the baflle being laterally constricted for the length of the baffle, the opening being disposed above said constricted portion, said opening being elliptical and having its major axis disposed transversely of the heater. V

In testimony whereof I hereunto aflix my signature.

GEORGE W. MUNDIE. 

